EP2176353A2

EP2176353A2 - Articles with low hydrogen permeation and their use

Info

Publication number: EP2176353A2
Application number: EP08785003A
Authority: EP
Inventors: Dragan Griebel; Stefan Brand; Udo Steffl
Original assignee: Clariant International Ltd; Rehau AG and Co
Current assignee: Rehau Automotive SE and Co KG; AZ Electronic Materials Luxembourg SARL
Priority date: 2007-07-24
Filing date: 2008-07-23
Publication date: 2010-04-21
Also published as: DE102007034393A1; JP2014194278A; WO2009012988A2; JP5800269B2; WO2009012988A3; JP2010534124A; US20100266840A1; JP5545493B2; CA2694246A1

Abstract

The invention relates to use of a moulding, moulded from a composition encompassing (A) a thermoplastic, and a coating provided thereon, moulded from a composition encompassing a component (B) which has been selected from a polysilazane of the formula (- SiR'R''-NR'''-)n, where either R', R'' and R''' = -H or R' and R''' = -H; and R'' = -methyl, as articles with low hydrogen permeation, where the permeation coefficient of the article with respect to hydrogen gas at from 25 to 30°C is preferably smaller than 10 cm3 mm/ m2 d atm, measured in accordance with DIN 53380-3 and ASTM D 3985, and their microhardness is greater than 150 N/mm2 to DIN EN ISO 14577. The invention further relates to articles with low hydrogen permeation encompassing a moulding moulded from a composition encompassing (A) a thermoplastic, and a coating provided thereon, moulded from a composition encompassing a component (B) which has been selected from a polysilazane of the formula (- SiR'R''-NR'''-)n, where either R', R'' and R''' = -H or R' and R''' = -H; and R'' = -methyl.

Description

Articles with low hydrogen permeation and their

use

The present invention relates to an article with low hydrogen permeation, for example, for pipes, hoses, moldings or containers.

Barrier materials characterize all industrial and economic sectors, especially food and beverage packaging, and they tend to prolong the shelf life of food. In addition to the barrier effect against oxygen and water vapor, the retention capacity for nitrogen, fragrances and aromatic substances is becoming increasingly important. In addition to permeation, barrier materials in some cases also reduce the migration of, for example, low molecular weight organic compounds and thus protect the packaged goods from foreign taste.

Permeation takes place in the steps of adsorption and sorption on the surface of the material, diffusion through the material itself and subsequent desorption.

A partially crystalline, nonpolar polyolefin has a good barrier effect against water vapor; the water vapor permeability according to DIN 53122 is typically 1 g / m ² d, but at the same time also a poor oxygen barrier effect, the oxygen permeability according to DIN 53380 is typically 5000 to 8000 cm ³ / m ² d bar.

Barrier plastics such as EVOH or PVDC or LCP have both a high barrier to water and to oxygen. All these materials fail, however, when it comes to high-barrier applications or even to the barrier effect against hydrogen gas.

In the case of the packaging films, in order to further reduce the permeation rates, it is necessary to steam-coat polymeric barrier layers with aluminum. In this case, aluminum layers in the range of a few nanometers to micrometers are vapor-deposited in a high vacuum. This brings in most cases the desired barrier effect.

The disadvantage, however, is the high cost of such a coating and the fact that the vapor-deposited plastics are no longer transparent. Another way is described in the journal Surface and Coatings Technology 111 (1999) pp. 72 to 79. SiOx layers are deposited by means of PVD processes and additionally sealed with so-called Ormocer-lacquers, ie inorganic-organic hybrid lacquers. Due to the multi-stage application method, this route is economically completely unattractive and has therefore not found its way into practice.

DE 102004001288 A1 discloses a hydrophilic surface coating for materials such as metal, glass, ceramics, plastics, paints or porous surfaces.

The coating contains one or more polysilazanes and an ionic reagent or mixtures of ionic reagents.

For storage and transport of hydrogen, parts made of stainless steel are usually used today for want of alternative materials. Therefore, hydrogen-carrying pipes are inflexible and difficult to install, and the corresponding stainless steel containers are heavy in weight and limited in shape.

JP-A-10016150 discloses a gas barrier film having transparency and good flexibility, and the heat resistance provided in the form of a ceramic layer formed by applying a polysilazane coating composition on at least one surface of a polyvinyl alcohol film, followed by converting the polysilazane coating into a ceramic layer , This laminate can be used as a gas barrier film. JP-A-11151774 discloses a transparent gas barrier film. To this end, a vapor-deposited inorganic oxide film provided on the surface of a base material is coated with a coating film by applying a solution with a polysilazane, followed by heating and drying. JP-A-2000246830 describes a silica-coated plastic film wherein the silica-coated plastic film is said to have good resistance to alkaline agents, as well as excellent adhesive properties and gas-barrier properties, the film consisting of a PET base film coated with a polysilazane solution.

With regard to the gas barrier, all these documents do not disclose their properties to any further information, in particular to which gases the respective films should have barrier properties.

WO 2004/039904 and WO 2006/056285 describe polysilazane-based coating solutions and their use, in particular for coating polymer films. The coatings produced thereby are described as protective coatings to provide corrosion resistance, anticorrosive properties, abrasion resistance. Resistance, anti-fouling properties, sealing properties, chemical resistance, oxidation resistance, heat resistance, antistatic properties and barrier effect. With regard to barrier effects, these international patent applications merely disclose information regarding oxygen permeability.

Hydrogen, however, differs significantly in its permeation properties from other gases, such as oxygen or carbon dioxide, so that information regarding any barrier property to oxygen that may be present has no bearing on the ability to increase the barrier to hydrogen.

This is where the invention, which has set itself the task of providing articles for the storage and transport of hydrogen available, which does not have the disadvantages and problems mentioned, so are of low weight, easy to mold and scratch resistant and especially one low permeation coefficient against hydrogen gas at 25 to 30 ⁰ C of less than 10, preferably less than 7.50 and in particular less than 3 cm ³ mm / m ² d atm, measured in accordance with DIN 53380-3 / ASTM D 3985 have.

According to the invention, the object is achieved by using an article having the features of claim 1, as well as by providing an article having the features of claim 8.

Preferred embodiments and further developments of the invention are set forth in the subclaims and the independent claims.

The article according to the invention is composed of a

(I) Component (A), which consists of a thermoplastically processable plastic and

(II) a component (B) consisting of a polysilazane which is applied by a coating process to component (A).

The component (B) may further contain residues of a catalyst such as ammonium salts, ethylenediamine, amines, pyridine derivatives, radical initiators, or organometallic compounds (eg, 0.05 to 5 wt .-% of a palladium compound), so that the reaction is carried out at lower temperatures can be. The article according to the invention preferably has a permeation coefficient against hydrogen gas at 25 to 30 ^° C. of less than 10, preferably less than 7.50, more preferably less than 5 and in particular less than 3 cm ³ mm / m ² d atm, measured on the basis of DIN 53380 -3 and ASTM D 3985, and is further more preferably greater than 155 by a microhardness (as a measure of scratch resistance) of greater than 150 N / mm ^2, and in embodiments greater than 300% of ISO 14577 of the coated component (A ).

The invention will be explained in more detail below.

Component (A) of the articles according to the invention is a thermoplastic selected from the group of polyolefins or polyolefin derivatives or polyolefin copolymers, e.g. Polyethylene or polypropylene, or from the group of vinyl polymers, such as polystyrene or polystyrene copolymers, or from the group of polyamides, such as polyamide 6 or nylon 66, or from the group of polyesters, such as polyethylene terephthalate or polybutylene terephthalate, or from the group the aromatic polysulfides or aromatic sulfones.

According to the invention, additives may optionally be present in the thermoplastic in the form of lubricants or processing aids, fillers such as talc, nucleating agents, stabilizers, antistatics, impact modifiers, flame retardants, fibers, conductivity additives.

Furthermore, in addition to the layer of component (A), the article according to the invention may also comprise further layers, depending on the field of use of the article with low hydrogen permeation. Thus, for pipes or hoses, as well as other storage containers (eg tank), an additional protective layer, a colored layer (to facilitate identification), etc., may be provided. Such embodiments are familiar to the person skilled in the relevant field.

According to the invention, it has been found that layers produced by applying a polysilazane-containing composition surprisingly provide improved barrier properties to hydrogen permeation. It is essential in this context that the polysilazane has the formula defined in claim 1.

Component (B) according to the invention is a perhydropolysilazane of the formula (-SiR'R "-NR '" -) n where R' = R "= R '" = -H (see embodiments 1 to 3), or a polysilazane having the composition R '= R "' = -H, and R" = -methyl (see embodiments 4 to 6), where n is an integer, and n is preferably such that the polysilazane is a numerical having average molecular weight of 150 to 150,000 g / mol, as disclosed in WO 2006/056285 A1.

In particular, it is preferred that component (B) is a perhydropolysilazane with R '= R "= R'" = -H. This requires particularly good barrier properties to hydrogen permeation.

The polysilazane to be used in accordance with the present invention is usually processed in the form of a solution. With regard to suitable solvents, concentrations of polysilazane and possible auxiliaries, catalysts, etc., reference is made to the disclosure of the two international patent applications WO 2004/039904 and WO 2006/056285, which are hereby included by this reference.

The application of component (B) is carried out by dipping, flooding, spin coating or spraying.

The curing can according to the invention at room temperature or preferably at elevated temperature, in particular at about 80 ⁰ C, are performed.

The layer thickness of the coating after finished application in the range of 0.01 to 100 .mu.m, preferably 0.5 to 5 microns.

This layer is preferably applied directly to the molded part, molded with the thermoplastic resin, without intermediate additional layer, such as, for example, the oxide layers frequently used in the prior art or else adhesive layers or support layers.

Preferably, a previous activation or pretreatment of the substrates, in particular via a plasma treatment, if necessary.

The coated articles according to the invention are preferably used in the electronics, electrical, vehicle or construction sectors as hydrogen transport pipes and hoses, hydrogen tanks, molded parts for these applications and the like.

Table 1 below shows the properties of the coated articles according to the invention. Table 1:

Examples 1 to 3

A 50 micron thick polyethylene film is pretreated by means of plasma and coated with a perhydropolysilazane solution in a mixture of dibutyl ether and anisole by spraying, 10 min. vented at room temperature and then cured for 2 h at 80 ⁰ C, so that a 2 micron thick barrier layer results.

The hydrogen permeation coefficient is determined on the film as described below on the basis of DIN 53380-3 / ASTM D 3985.

Examples 4 to 6

A 50 .mu.m thick polyethylene film is with a solution of a polysilazane of the formula (- SiR'R "-NR '" -) n, with R' = R ¹ "= -H and R" = -Methyl in di-n-butyl ether by Coated dip coating and flashed for 2 min at room temperature and then cured for 30 min at 70 ⁰ C, so that a 1 micron thick barrier layer results.

The hydrogen permeation coefficient is determined on the basis of DIN 53380-3 / ASTM D 3985 as follows: W

With component (B) coated 50 micron thick films of component (A) were glued to mask between two aluminum foils with round cutouts.

After installation of these test samples, the measuring cell was purged on the feed side with forming gas or hydrogen, on the permeate side with air.

The H2 content of this purge air was determined using an H2 sensor (Sensistor Hydrogen Leak Detector H 2000).

The evaluation was carried out by averaging several measured values after adjusting the equilibrium taking into account the purge gas flow.

Table 2 below shows the properties of comparative examples of known packaging materials.

Comparative Example 1

Comparative Example 1 is a 0.126 mm thick aluminum foil.

Comparative Example 2:

Comparative Example 2 is a 0.182 mm thick polyethylene film.

Comparative Example 3

Comparative Example 3 is a 0.230 mm thick film of a liquid crystal polymer LCP.

Comparative Example 4

Comparative Example 4 is a 0.262 mm thick polytetrafluoroethylene film.

Table 2:

The articles of the polysilazane-coated thermoplastics used according to the invention have a hydrogen permeation coefficient which is approximately at the level of a 0.126 mm thick aluminum foil and is substantially reduced compared to the pure polyethylene foil.

In addition, permeation tests were carried out as a function of the temperature (at 23 ⁰ C, 40 ⁰ C and 60 ⁰ C):

a) measurement with H2 dry;

b) Measurement with H2 humid = H2 and purge gas with 100% relative humidity.

The results show that neither the temperature nor the humidity have a negative influence on the barrier effect of the coating.

It even shows that the relative improvement of the barrier increases with increasing temperature.

Furthermore, conditioning the samples (clamped, one side exposed to vacuum for 2 days at 23 ^° C.) with a mixture of isooctane / toluene and water results in an improved hb barrier.

Claims

Claims 1 to 10

Use of a molded article formed from a composition comprising (A) a thermoplastic, and a coating provided thereon, formed from a composition comprising a component (B) consisting of a polysilazane of the formula (-SiR'R "- NR "'-) n is selected, wherein either R', R" and R '"= -H, or R' and R '" = -H; and R "= methyl, as articles with low hydrogen permeation.

2. Use according to claim 1, wherein the article has a permeation coefficient against hydrogen gas at 25 to 30 ⁰ C of less than 10 cm ³ mm / m ² d atm, measured in accordance with DIN 53380-3 and ASTM D 3985, and a microhard greater 150 N / mm ² according to DIN EN ISO 14577.

3. Use according to claim 1, characterized in that the thermoplastic of component (A) is selected from the group of polyolefins or polyolefin derivatives or polyolefin copolymers, such as. Polyethylene or polypropylene, or from the group of vinyl polymers, such as polystyrene or Polysty- rolcopolymerisate, or from the group of polyamides, such as polyamide 6 or nylon 66, or from the group of polyesters, such as polyethylene terephthalate or polybutylene terephthalate, or from the group of aromatic Polysulfides or aromatic sulfones.

4. Use according to claim 1, characterized in that the application of the component (B) by dipping, flooding, spin coating or spraying takes place and the curing at room temperature, preferably at elevated temperature, in particular at about 80 ° C.

5. Use according to at least one of claims 1 to 4, characterized in that the thickness of the coating after finished application in the range of 0.01 to 100 microns, preferably 0.5 to 5 microns.

6. Use according to one of the preceding claims, preferably in the electronics, electrical, vehicle or construction sector, preferably as a hydrogen transport tube and hose or hydrogen tank or a molding used therein.

7. Use of a component (B), which is selected from a polysilazane of the formula (- SiR'R "-NR '" -) n, where either R ", R" and R' "= -H or R 'and R '"= -H; and R "= -methyl to produce a coating for reducing hydrogen permeation through a molded article made of a thermoplastic.

A low hydrogen permeation article comprising a molded article of a composition comprising (A) a thermoplastic and a coating thereon formed from a composition comprising a component (B) consisting of a polysilazane of the formula (-SiR 'R' 'NR' '' -) n is selected, where either R ', R' 'and R' '' signifies -H or R 'and R' '' signify = -H; and R '' signifies -methyl.

Article according to claim 8, characterized in that the thermoplastic of component (A) is selected from the group of polyolefins or polyolefin derivatives or polyolefin copolymers, e.g. Polyethylene or polypropylene, or from the group of vinyl polymers, such as polystyrene or polystyrene copolymers, or from the group of polyamides, such as polyamide 6 or nylon 66, or from the group of polyesters, such as polyethylene terephthalate or polybutylene terephthalate, or from the group the aromatic polysulfides or aromatic sulfones.

10. Article according to at least one of claims 8 or 9, characterized in that the thickness of the coating after finished application in the range of 0.01 to 100 .mu.m, preferably 0.5 to 5 microns.